Yes, once it is in, you can not take it out and use it later, as it is not resealable.
Read the directions for YOUR gun. CO2 does not explode, but may leak down.
Yes, hotter Co2 expands faster than cold, but only if that temperature is constant, but heating CO2 tanks is extremely dangerous, and will not do anything but weaken the cylinder, which may explode and shrapnelize.
CO2
If it is a gas gun, no. However, some are spring guns, and some are electric.
If you can hear it.
[ 34.3(gC3H8) / 44(g/mol C3H8)] * [ 3mol CO2 / 1molC3H8 ] * 44(g/mol CO2) = 103 gram CO2
The top of a CO2 canister isn't very thick. It will take about a half a pound of pressure to break through the top.
All guns leak a little bit when you put Co2 in the gun. its normal
I think when they receive carbon dioxide
12 grams are non refillable.
It's really not recommended. By doing so you leave the gun pressurized and this may rupture the seal. It also makes it possible for someone else to accidently fire the gun.
Co2 will leak out in a few hours. It's not designed to stay in the gun for a long period of time.